In the poultry processing industry, a number of methods have been devised for stunning (preferably without killing) live poultry prior to processing into various food products. While the previous methods such as electric shock stunning are substantially directed to performing this operation in an efficient manner, there has been a growing trend toward implementing more humane methods of euthanizing the birds, while still preserving the quality of the meat. One approach that has been used is the implementation of carbon dioxide (CO2) and or other gasses to “stun”, or reduce the consciousness of, the poultry prior to slaughter. Ideally, carbon dioxide or other stunning gasses should be used in a manner that reduces or eliminates the consciousness of the birds while keeping them alive, as regulations require that poultry be bled out prior to processing.
However, to preserve the quality of the meat, the birds should be kept as calm as possible prior to the euthanization so to preclude excitement, increased heart rate, adrenaline release into the bloodstream, and/or other factors that can cause increased blood flow to the birds' extremities. Should any of the foregoing occur, the quality of the resultant meat is likely to suffer, as it is widely held that unstressed animals produce more palatable meat with a better texture. Further, unstressed animals tend to hold less blood in their extremities, thereby allowing the poultry to bleed out more completely. Thus, the process and apparatus employed to stun and euthanize the poultry should cause as little disturbance as possible to the birds prior to and during the application of the stunning and euthanizing.
Moreover, the stunning process should cause the bird to become unconscious (e.g., by reducing the brain activity of the bird), which minimizes the excitability of the bird, while not stopping or reducing the function of the bird's heart, a situation which can make it difficult to drain most of the blood out of the body of the bird, especially the extremities. Further, the size and health condition of the poultry can greatly affect whether a given amount of exposure time or concentration of carbon dioxide or other gasses either stuns, kills, or merely stresses live poultry.
As noted above, CO2 stunning is one method of incapacitating poultry prior to euthanizing. One example of a known CO2 stunning systems is shown in U.S. Pat. No. 6,848,987 to Draft (hereinafter referred to as “the '987 patent”). While this system relates to using CO2 to stun birds prior to processing, the process used introduces stressors to the birds prior to and during the stunning process, which can lead to an increased heart rate in the birds and the aforementioned problems resulting from the increased heart rate.
For example, in the system of the '987 patent, the cages are subjected to numerous movements that can cause physical jarring of the birds and audible noises about the birds, which can lead to unnecessary excitement of the birds. Specifically, the cages, which are typically transported in stacks of two or more cages, must be unstacked from each other prior to moving through the system and the stunning of the birds. Since the structure of the cages is analogous to a stack of drawers, the unstacking of the cages functions to remove the top or ceiling from the cages, and this change in environment may disorient or excite the birds. In addition, the apparatus of the '987 patent primarily moves the cages in a horizontal direction, yet requires that the cages be lowered or moved downwardly into a gas chamber, a further change in the birds' environment that can cause a disturbance among the birds, and providing an area where CO2, which is heavier than air, may accumulate at levels higher than anticipated. Further, the '987 patent reports that the presence of humidity to a gas chamber utilizing carbon dioxide can lead to the production of carbonic acid, further stressing the poultry.
Further, as discussed above, a method or system for adjusting the levels of CO2 to allow for differing poultry sizes and health conditions of the animals would be greatly appreciated. In addition, since the application of carbon dioxide to the birds tends to dry their throats and cause panic in the birds this side effect should be minimized as much as possible.
Therefore, a system for stunning poultry that reduces the stress to the animals, allows for controlled adjustment of the stunning levels depending upon the particular poultry being used, based upon the type of poultry, their size, and their health, without risking the killing of the poultry or stressing the poultry without properly rendering them unconscious would be greatly appreciated in the art.